So much of the movie business these days is about more: more special effects, more decibels, more speed. But Billy Bob Thornton, 46, a soft-spoken son of the South and tattooed spouse of Tomb Raider Angelina Jolie, inhabited two taciturn roles this fall and, thrillingly, gave us less. By slowing down and holding back, he made his few moments of passionate outburst unforgettable, riveting our attention as thoroughly as any flash-cut game of Quidditch could. As a sunny-California barber hatching shady blackmail schemes in the Coen brothers’ The Man Who Wasn’t There, Thornton laid out his acting tools lovingly and quietly. His droll haircutter squints at customers like Clint Eastwood eyeballing a villain. And when his tonsorial drone clumsily reaches for love in the unlikely form of a young girl with a modicum of piano-playing talent, Thornton’s stunned expressions, as things unravel, convey vast reserves of aching romanticism. Thornton plays it mostly cool again in Monster’s Ball as a Georgian death-row corrections officer. But he sets a steamy sex-scene benchmark with Halle Berry, baring the length of his backside and the depths of his soul as he tells Berry’s widowed character, with utter conviction, ”I want to take care of you.” Considering that he was also the best thing in October’s misfired bank-robber comedy Bandits, Thornton has proven he’s a man of his word.